Screening system and apparatus



May 6, 1969 M. SCOTT SCREENING SYSTEM AND APPARATUS 2 M 4 t 5 8 4 4 m 2 4 S 3 u Iv L. i R L mm E] A an I R 1 R0 0 4 R m 4 u 2 WP ll U 05 R F 8 3 6 W 3 1 8 b e F d e 1 1 F DISPOSAL JNVENTOR. MARVIN SCOTT ATTORN EY May 6, 1969 M. SCOTT SCREENING SYSTEM AND APPARATUS Sheet Filed Feb. 8, 1967 INVENTOR.

MARVIN SCOTT ATTORNEY May 6, 1969 M. SCOTT 3,442,253

SCREENING SYSTEM AND APPARATUS Filed Feb. 8, 1967 Sheet 3 of6 INVENTOR. MARVIN SCOTT AT TO QN CY May 6, 1969 M. SCOTT 3,442,253

SCREENING SYSTEM AND APPARATUS Filed Feb. 8, 1967 Sheet 4 of 6 Fig 5 1 12 1s Q 62 w/ a4 a V I A' {5 v2 6! I: 14 4 SI/ i: a; E a; w a: i a; A V 50 zfl nvnvnflgg 0&0

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IN VEN TOR.

MARVIN SCOTT ATTORNEY May 6, 1969 M. SCOTT 3,44

SCREENING SYSTEM AND APPARATUS Filed Feb. "8, 1967 Sheet 5 of 6 lol . v MARVIN SCOTT May 6, 1969 M. SCOTT SCREENING SYSTEM AND APPARATUS ore Shee't Filed Feb. 8, 1967 INVENTOR.

MARVIN SCOTT MW ATTORNEY United States Patent 3342 253 SCREENING SYSTEM;- AND A BRARNIUS Marvin Scott, Hamilt0n,,0hio;.assignor to UQSaIilywoode Champion Papers- Inc.-, ,Hamiltom, 0hi0;, a; corporation; of New- York- FiledlFb. 8','.1967,]Ser.No.614,142 Int. Cl; B? 9/10, 11710, B0'1f'3712' U.S..'Cl. 118-603 11 Claims ABSTRAGT OF THE DISlZI-iOSURE A system. and. apparatus for screeninglumpsout. of. liquids. has withina housing a tubular screening ,element that is moved in ,an.hourglassshaped orbit While. the. material, Being. screened movesfrom theinlet into: the:

. liousihg, through the. tubularsscreen, thence, through. a.

flexible. outlet. passage. communicating withrthe inside. of. the tubular screening ,el'ementn Thisinvention relates to a screening systemand appara tus. Whilethe invention is-applicable tothescreening, or filtering of a wide, range; of.mate1ials,,it,'has particular; value in, screening, li'quids,, such. as sl'urries, suspensions, and emulsions ,for coating paper, ,inconnectibn withwhich. itwill'be descrihed'.

In making a-coatedj papena coatingisapplied. to. the. surrface of the paper and'is driedLT-he.coatingcommonly comprises Water, mineral" pigment, (e.g.,. clay,. calcium. carbonate, titanium dioxide, aluminum,hydrate,,or.a mix,- ture), adhesive (fe.g v casei'n, starch, latex, soya protein,, polyvinyl alcolioLf or a mixture) and. often, a. dye, derfoamer,. emulsifier or, surface active agent. are added. Iiumpsappearinthe coatings for a variety offreasonsfandf causedefects in the coatedpaper. The dfe'ctsarenotonly those of a poor appearance ofthe coatedlsurface butial'so. may. include-those; causing ablemish when printed upon. and holesin the paper due to a lump pushing; itsrway. through. the paper Sometimes the, defects are ofthe. press=stopper varietythat is,, a printing, machine, is, damaged or likely to be damaged by paper, containing. such aidefect.

Timely detection of defects is difiicult because the. coatihg procedure" is ordinarily performed continuously by, applying coating continuously to a movingweh of. paper. Quite often the coatingi's; done on a paper machine. as. part of the paper manufacturing; procedure, or alternativelyon .a coating'machine: 'inboth such cases the coated. paper is commonly'woundup into a roll, which conceals the defects, andshipped to the. printer; Thus, defects are. not easily detected either: by, the: paper'manuf'acturer or his customer; the' printer:

Various types=of screens-and filtershave been used in. coating preparation systems and coating, application. sys-, terns to remove lumps while the coatingisbeing made andi beforethe coating;i's applied-tothepaper; often in the past requiringanumbenof screens of largeareas that;re: quire frequent clean=upsz Also, coatings and liquid coating ingredients having a; very high total solids have either: Been too difiicult to: screen-or'uneconomic to screen; even though the rheology, indicates screeningto he possihlez A case-in pointiscale cium carbonate= slurri'es" (calciumcarbonate dispersed'in' water-1) liav-ing tota'l solids of about 65% or=hi gherwhere about 80% ofthe calcium carbonate parti'cIesare-Z mi crons" or less; which have as' a rule not been screened" at all if that solids contentis'to berretained," or have, been diluted By adding water, to render them more susceptible to" screening: Dilution'is not desirable;

One" objective ofthepresentinventionis the provision of an improved apparatus" for screening 'materia'ls;

Other? objectives" of the" presentinvention' arethe provisions ofan' improved system'forscreeuing materials:

Other"objectives-'ofthis. inventionare" to provide an improved'apparatus and improved'systemfsuitablefor screen: ing paper'coating'materialsiatany of several pointsinthe preparationor application to; paper-'ofa' coating:

As amatter ofconveniencein describing-the invention, I use thejtermliquidtorefentomiXtures; solutions; slurries; suspensions; dispersions, emulsions, andthe likein short; those' materials containing one: or-'more. liquids: containing asolid -advantageously aqueous liquids use farm coating paper:

Apparatus accordingto the invention. comprises" an elongated. horizontally: disposed tuhular' screening member; meanssupporting said screening mem berg'atacentral portion'thereofgmeansfor moving one end ofsaidscreening member through a predetermined orbit eccentrically about the longitudinalaxis'thereof; a housing surrounding said screen; andhaving-an .outletithrough the housing fonfluidsthathave been screened;and' conduitmeans con nectedbetween said outlet and" theinside of said tubular screening member'whereby materialsimay flow'into said' housing through said screening member; thence out of said housing through said conduit.

Longer production runs, reduced down-time; reduced coating loss *f'rorn'disposallof lumpyjcoatings; andreduced defects in the product areaamong the advantages realized fiom this invention when, fonexample; it is applied to treating *papercoating materials;

Other objectives', advantages and fatureswill'become' evident fi 'om the following description and drawingsv wherein:-

FIGE 1 schematicallygillustrates a typicalprior art'coating system;

FIG. 2 schematically illustrates a.coating,sy stemincor= porating the presentinvention;

FIGE 3* is a schematic side;- elevation of j'apparatusconstrueted accordingto the invention; ,as seen from:the out-= sidethereof;

FIGS 4 is anenlarged side elevation of the apparatus of. FIG; 3 with a'portion of the housing cuttaway, notdrawn to scale; and showing certain features of the present in-r vention such as the general location'of main.comp onents of the apparatus FIG": 5is'anenlargedcross section, not to scale; along section 55 of FIG: 3 and illustrating the manner of holding the-'removahle-housing' sidewall in place and the structural arrangement of the screen and the apparatus supporting same;

FIG! 6 is anenlarged cross;section-nottoscale of parts. of-FIGE 3, inside elevation, particularly illustrating the flexible outlet" conduit and 1 the it powerhead, assembly;

FIG. 7 is an enlarged crosssection'notito scale of 77" of FIG 6 showing certain details of. the powerlieadQparticularly' theeccentric' member.

FIG; 8 is an enlargedbutinot' to scale, crosssectionas.

seemalong section 8-8"ofFIGZ 6 and illustratingcertain features ofthecradle' andcylinder assernhly includingthe fashion inwhich they are clampedtogether.

FIG. 1 schematically represents a typical prior art coating system for paper wherein a substrate, shown as a web of paper 10, is moved past a coating apparatus 12 which applies coating to the underside of the paper web. The coating apparatus 12 comprises a coating pan 14, rotating applicator roll 16, and a doctor apparatus 18 of any suitable variety. A body of coating 19 reposes in the pan and the applicator roll as it rotates picks up the coating and transfers it to the underside of the web. The excess coating is struck off by the doctor apparatus 18 and returns to the body of coating 19 in the pan.

Referring now to FIG. 2 there is shown schematically a coating system incorporating a screening means according to the present invention. The coating pan, applicator roll, doctor blade, and other parts are for illustrative purposes as before. The system also includes a screening means 30 and suitable inlet and outlet connections between it and the coating pan 14. An inlet conduit 32 is connected between a suitable point in the coating pan and the inlet 130 (see FIG. 6) of the screening means. A reservoir may optionally be provided in conduit 32. A pump 33 is upstream of the manually operated inlet gate valve 34 in the conduit 32. After coating has moved through the inlet conduit (and the pump and valve therein), it passes through the screening means 30 and is returned to the body of coating in the pan 14 through a line 36 which contains therein a manually operated return gate valve 38. It will be appreciated that the pump is shown as a gear pump but could be of any suitable sort.

The system of FIG. 2 also includes a backflush gate valve 41 which is connected between a suitable source of water under pressure and the return line 36 at a point upstream of the valve 38. A conduit 42 leads to a sewer or suitable repository for waste materials and has therein a manually operated disposal gate valve 44 which is connected into the conduit 32 at a point between the inlet valve 34 and the screening means. Also, an electric motor 45 is provided to drive the movable portions of the screen assembly 30.

In normal operation of the system of FIG. 2, valves 34 and 38 are open and valves 41 and 44 are closed.

The valves 41 and 44 comprise a back flushing system to direct wash water through the screening apparatus in a reverse direction whereby dirt and other materials which have collected on the screening element are removed from the screen and a portion of them carried through the line 42 to disposal such as a sewer. During back flushing, valves 34 and 38 are closed, the pump 34 is turned off, and the backfiush and disposal valves 41, 44 are open.

Preferably backfiushing can also be done by closing valves 34, 38, 44 and opening valve 41 and clean out port 70 (FIG. 3) whereby cleaning water carries screening rejects out through port 70. A conduit or sewer line with a disposal valve therein can be attached to the port 70 for convenience, the valve being operated the same as described above for valve 44 and, of course, in conjunction with backflush valve 41.

FIGS. 3-5 show in assembled form the arrangement of the parts of the screening apparatus 30. These include a housing 50, a screen 52 supported in tubular form by a screen supporting assembly 54 and a power head 55 as components of the apparatus. A universal joint 56 medially supports the tubular screen 52 via connection to the screen supporting 54 and operates in conjunction with the power head 55 to contribute to the orbital motion of the screen support assembly, such motion defining a substantially hourglass-shaped orbit.

The housing 50 comprises a plurality of side walls 61, including a removable top side wall 62, and end walls 63, 64 at opposite ends of the housing assembly. An inlet 130 (connected to inlet conduit 32 of FIG. 2) is at an upper end of one side wall, adjacent that end wall 62 which supports the power head 55. An exit conduit connection 67 for the screened fluid extends inwardly from the opposite end of the housing in end wall 63. The housing thus provides an elongated screening chamber 68 in which is supported the screen 52 and its support assembly 54.

Referring to FIGS. 3, 4 and 5 the removable top side wall 62 is illustrated as a plate 62 held in place by a plurality of hinge bolts 71 and wing nuts 72. The gasket 73 (FIG. 5) of resilient material is placed between the undersurface of the plate 62 and a flange 74 (conveniently made by welding angle iron around the outside of housing side wall) provides a fluid-tight resilient seat. The hinge bolts are mounted on pins 75 to swing in and out of the slits 76, 77 in the plate 62 and flange 74. The system operates under pressure, so a pressure gauge 78 and suitable fittings 79 to mount the gauge in pressure communication with chamber 68 may be'provided on the plate 62.

Fitting assemblies for a number of high pressure cleanout port assemblies 69 (FIG. 4 only) may be provided so that high pressure water or other cleaning fiuids can be admitted to chamber 68 to wash off the outside of the screen. Fittings providing a large clean-out port assembly 70 (FIG. 3 only) or a hand hole may also be provided at one end of the housing, illustrated here as being in the left hand end wall. Lumps and sediment can be removed via the hand hole manually or during the backflushing operation. Fitting assemblies 69 and 70 may conveniently each be a threaded hole through the housing wall with a pipe plug screwed thereinto for sealing same when not in use. Fitting 69 facilitates chamber drainage during backfiushing, if open.

The housing 50, support assembly 54, and fittings are in general constructed of stainless steel or similar noncorrodable material. A welded construction is preferred wherever possible. The apparatus 30 operates under internal superatmospheric pressure during screening operations and is constructed to withstand such pressures.

As best seen in FIGS. 4, 5, 6 and 8 the screen support element 54 includes cylinder sub-assembly 80 which is in turn supported by a cradle sub-assembly 81. The fine screen 52 is preferably of nylon, stainless steel, or the like, is removably supported in tubular form (shown as circular in cross section although other configurations are contemplated e.g., square) on the cylinder 80 by the clamps 82 and is removable therefrom. The cylinder subassembly 80 comprises an open mesh (e.g., to ,-inch mesh) tubular stainless steel screen 84 (illustrated as circular in cross section but other shapes are included) to which is welded support rings 85 at the ends and at any suitable intermediate point. The end supporting rings 85 protrude past the stainless steel screen 84 at the ends where they are received by the fixed clamping ring 87 (which is part of the cradle) and held against the fixed ring 87 by the removable clamping ring 88 by the nuts and bolts 89, 90. The fixed clamping ring 87 is welded to and -a part of the cradle sub-assembly.

The cradle sub-assembly 81 comprises cradle end plates 91, 92 spaced apart by and secured (as by welding) to a support bar 93 which conveniently may be made of angle iron. The support bar itself has a connection at its midpoint to the universal joint 56. Each cradle end plate has secured (as by welding) on the inside face thereof the lower half 87 of the corresponding clamping ring assembly. The lower clamping rings 87 are arranged to receive in a cradle fashion the support rings 85 of the cylinder.

In the right hand cradle end plate 92 (see FIGS. 4 and 6) is provided structure to receive and support portions of the power head 55. The power head is described below. The left hand end plate 91 of the cradle has outlet conduit 95 extending outwardly (shown as to the left) toward the end wall exit connecting 67 so that fluid may fiow therethrough. During continuous operation the fiuid will flow out through the connection 95 into the housing end wall connection 67 thence to some designated delivery point. A short section of resilient or flexible conduit 96 such 'asra nippleor. rubber; hosev 96; provides a flexible conduit connection betweengthe.cradlerendsconnector 95 andthe housing endiwalllconnector: injefiectconduitz 96 establishes a flexible closed passagefrlomzinside:the;screen 52*:to.outsideathexhousihg:.Pipe;clampst91- or the: like are shown. as; holding; the: flexible i connection: 96: in" place: on each of; the". endiwall: and: cradle-connectors.

As seen incFIGS. 4,.6wand 7 the-powenhead assembly 55 employsiatrotatable: eccentric:elementa100 which drives a circular followerz'and housing,110-mounted OIlIthCl end plate 92; When the: eccentric? is rotated! (e.g:,. by;- motor 45), it causes therentirescreenzSZ andtits supportsassembly. 54itolmove1in: an: hourglasssshaped orbit; about the longitudinal axisr102: the: right. end: 92: of: the support assembly moves: through: acircular orbit, butithew assembly: 54) being: restrainediat its: center by; the-universal joint, a sort of wobble actioniis: achievediatr each end of the; screen. andtits; support), called-herein a' substantially hourglass-shaped orbit.

In the illustrated embodiment, the powerrhead"55 em1-.- ploysv a ball bearing assembly 1 between the". eccentric and the follower: The eccentric is l preferably an olficenter cylindrical end of the drive shaft 106. The drivezshaft 106 rotates in ball bearings 107. A drive shaft collar FIG; 6--no number.) spacesibear-ing l05' from adjacent bearing 107 and a sleeve (FIG. 6no:number:)': spaces the bearings 107. Theleccentric l fltl isshown a's integralrwith the shaft, andican be off-reenter lay-from; ,4, to as measured from the:axis ofrotation: ('or centen linepi 102 of the shaft I06; Eccentricity is designated. as; 103 in F 1G; 7 The electric-motor- 45 connected" through: a. suit able coupling rotates the shaft 106 .whereforrthez eccentric drives theesereentassembly through therhourglassashaped orbit.

In FIGS; G and 71 the power hea'dzhousihg comprises the fbll'owen and; housing-110 which is bolted. to: and protrudes toward the drive". shaft: from: the; right cradle endplate192 an. eccentricihousin'g 11]; supported: from the housing right" end wall64: as shown; in; 6,1 and a resilient sleeve: suchaasr rubber nipple: 1712; is clamped in place to keep1liquid'outfofe' the powerrheadn As shown in EIGS'F4 andtS the: screen 52nandl screen support 541 assemblies are supported. an at central'l part thereof, that is medially; by'af fiexibleimountingzsuch' as a ball. and socket j oint? or preferably: the universal joint. 56. The universal joint is secured:betvveensupport'bar(angle iron)? 93:-a'nd the: housing; through. the"- agency. of, a" stud 112 and a threaded: stud .114:1bcatedrrespectively: at the upper and lower endsv of: the: universal. joint:. The: upper end of?stud1112extends;:intozaerecess:in1lugc 115. which is welded: or otherwise: secured: to.'the bar: 93& Tapered) pins 116 are: force+fitetlr intm the: universal; joint: and: the lug to: maintain: the studi hence .theauniversalzjoiiitl. fixed in position: at the upper end? thereof.

The lower threaded stud 114 is securedtby-a=pin1 17 to the: lower. fill'dfOf the: universal joint; The pin. 1 1l7 isitapered and. force-fittedi in the: universal joint. The lower; end of stud 114 has threads 118 thereon. The: threaded end extends through" a hole: in; a. blind: flange: 119,- and: is; secure'dxin place: by"a.nut1 120: It:will-readily be seem that the aforesaid constructiontprovides means tor loosen the universal joint in: order to: assemble: or; disassemble the apparatus, particularly tozremoverthe: screen; and screen assembly from, within the: housing.

Ther blind flange: 119' is secured? by any appropriate; means such as a plurality of bolts 122 to acorresponding flanges 123: whicha is-c supported-from: the: housing. as; by

welding: byral shortl nipple-l 124i whicha is; in:turn mounted on: the housing. Iti will: be obsenvedl that: the structureshoiwnnasibest seemin: FIG; 5: providesma; recess-atlthe bottom oh. the; housing; inzwhich. the. IOWCIJCIICI" of the:-

universalijointtis received:

In: operation; coating. material.- on otherv liquid 0 to: be

screened= e;g:,.19;.FIG ir 2 isradinitted toithe housing: 50. through the inlet opening..130 and fills thechamber 68 ofTa motor driving the power head 55. The power;

head drives one end of the screen unidirectionally and repetitively. througha-circular path-and theother end of the, screen moves substantially equally and oppositely: Thus, the screen and its support assembly is centrally,

, supported so. that the hourglass shaped orbit is: realized through the. coactionof: the pivot jointorhinge joint' as-- sembly56'and'the eccentric motion provided :by the powers head.

The structure described affords numerous practical advantages; it is;readily cleaned by;using:the fittings 69 'to admit water under pressure. and: the port at: towbackfiushand remove accumulatedlumpmxthe screen 52-can-be replaced readily because of: access. through; removable housing wall: 62, the: removable mounting on. the: cradle 81. and. cylinder variousmeshesof: screens752 can'be used; shafts with various: amounts of eccentricity 103 (FIG; .7).can be1substitutedffor: each other;,the screen can be wobbledativariousspeedsrsmall screen area .is.=-readi1y achieved; especially on: thixotropim liquids; all' of: which meanrthatLrepair andicleaninggup. are? readily: achieved and that thezapparatus can bermodifiedastc: screenmesh; amplitude. wobble? (or: cycle) speed, and; similarly; as to the. process and' the system..

The process of this invention to screen lumps: from mixtures of? liquids and: solids: (such. act-coating. 19) inoludes the: steps .oflrprovidingra tubular? screening element 52 1 disposed within' the: chamber "68 the: outlet" passage 67 fromthe chamber'extending fromzinternall'y of the element: 52;: filling; the: chamber: includingsthe element with the mixture to be screened; moving the elementfrepetitively. andunidirectionallythrough an hourglass-shaped orbit by. operating; the; power head; 55;? maintaining a superatmospheric pressure in the chamber; .andimaintaining flowfrom inletx6'5- (e'.g., frorn' c0nduit532')i into the chamber of the mixture toibe: separated while moving the. screening element 521an'dremoving screened mixture from internally ofthe elementzand. through: the; outlet passages 95, 96;. and: 67!.

An example follows in which the screen 52 was 40 mesh nylon screen, of""172 squareinclies total area, the

amount of eccentricity 103'- was gi -inch, the frequency ofvibratibn or rotationwas-1725 rapzm, and the coating comprised an aqueousmixture' of 8 parts caseinand 8 parts latex as adhesive,- IOU-parts calcium carbonate pigment, (all parts by weight) and had total solids of 54;

The screen-was installed as shown-iri FIG. 2" top continuous screening of the coating being: pumped from areservoiriir line" 32 to a cast coating application 1 2; The estimated screening rate at the start ofitherun was approximately; 15" gallons per minute: .Just'. prior to installing therscreenglurnps'were: beginning:to show uplin the coated: papenmade on? the: casting: drum; the coating from; the; pan: 14iprior tothe-test hada 325 mesh rejectstestl oh 0.32%. After the screen had operated? for; an. hour, the pan =325-meshrejectsrhad"dropped fromtO.32% toad-07%. The. 325t-meshi rejects test. is. run: as: follows-: a 1000. gram sample of coating is obtained and. screenedon. a 32i-mesh. screen. The rejects, i.e.,. the. material. retained on (or not passed by). the screen are collected, dried. in. an, oven to. a bone dry condition, then weighed. The weighed residue, in grams, is. then. expressed; as a lpercent (on a weight basis obviously), of. the actualtotalsolids in. the. original wet sample... The system. and. screen. 30 ran continuously for 27 hours and 50 minutes. before being backflushed via valves 34, 38, 41, 44. Flushing time required approximately five minutes. Approximately 108 grams of wet rejects had been collected by the screen 52 during this 28-hour period. The screen 30 was put back into operation immediately after flushing. The pan (14, FIG. 2) 32S-mesh rejects were still running at a level of approximately 0.06%.

Operation was continued for another 28 hours and 55 minutes when the unit was again backflushed for about five minutes. Approximately 100 grams of wet material were collected by the screen 52 during this second 28- hour period of continuous operation. At 8 a.rn. on the fourth day 325-mesh rejects from the color pan were still at a level of 0.07%.

Subsequent continuous tests on the same equipment included backflushing every 2 or 3 days during which the 325-mesh reject levels remained in the vicinity of 0.07% at the coating pan.

I claim:

1. Apparatus for screening liquids, slurries, and various mixtures of liquids and solids comprising:

a housing having side walls and a pair of opposed end Walls defining within the housing an elongated chamber extending lengthwise between said end walls;

an outlet connection adjacent one end of the housing through one of said end walls;

an inlet connection through one of the walls of the housing adjacent the other end of the housing;

an elongated tubular screen supporting member Within said elongated chamber, said screen supporting member having adjacent said one end an outlet connection from inside that region surrounded by a screen when a screen is supported on the supporting member;

a flexible connection and conduit connected between the screen supporting member outlet and the outlet connection on said housing end wall, whereby there is provided as a flow path for material to be screened said inlet connection, said region, and said flexible connection;

means for moving the ends of said screen supporting member eccentrically in an orbit about the axis thereof; and

a flexible joint connected between the housing and screen supporting member supporting said screen supporting member medially located between the ends of said member; whereby the conjoint action of the means for moving and the flexible joint moves the support member in an hourglass shaped orbit.

2. Apparatus according to claim 1 further comprising a back flush system to reverse flow through the chamber whereby a liquid may flow from the aforesaid housing outlet connection through the chamber and screen sup porting member thence through the housing inlet connection.

3. Apparatus according to claim 1 further comprising a back flush system that includes valving arranged to admit liquid to said housing outlet connection and to shut off exit flow from same.

4. Apparatus according to claim 1 wherein at least a portion of one of the side walls of said housing is substantially removable whereby access for cleaning and maintenance is obtained to the elongated chamber and apparatus therewithin.

5. Apparatus according to claim 1 further comprising a screen removably supported on said tubular screen supporting member.

6. Apparatus for screening liquids, slurries, and various mixtures of liquids and solids comprising:

a housing capable of operating under internal pressure and having end walls and side walls defining within the housing an elongated chamber;

an outlet connection through one of the end walls of the housing;

an inlet connection in one of the side walls of the housing adjacent to the other end wall;

an elongated tubular screen supporting member within said elongated chamber;

a screen supported in tubular shape by said member;

said screen supporting member having at one end an outlet connection from inside the region surrounded by the tubular screen supporting member and a cam follower supported on the opposing end thereof;

a flexible connection and conduit connected between the screen supporting member outlet and the outlet connection in said housing end wall;

a universal joint connected between said housing and said screen supporting member supporting said screen supporting member at a central portion thereof; and

a cam rotatable relative to said housing and mounted to drivingly engage said cam follower.

7. A system for screening coatings and the like comprising: like comprising:

means for applying said coatings to a substrate, said means having a reservoir for containing coating materials;

screening means;

means to transfer coatings from said reservoir to said screening means;

means to remove screened coatings from said screening means and return them to said reservoir;

said screening means further comprising a housing capable of operating under super-atmospheric pressure and completely surrounding the next-claimed screening element;

a tubular screening element disposed within said housan outlet from said housing communicating between said means to remove and return and the inside of said tubular screening element;

means connected between said housing and said screening element for movably supporting said screening element at a medial portion thereof; and

means for moving the ends of said element through a substantially circular path whereby an hourglass shaped orbit is defined by the element as it moves through its orbit responsive thereto.

8. A screening apparatus comprising in combination a tubular screening member;

means for flexibly and movably supporting said screening member at central portion thereof;

means for moving one end of said screening member through a predetermined hourglass-shaped orbit eccentrically about the longitudinal axis threof;

a housing surrounding said screen, and having an inlet for fluids to be screened through the housing and an outlet through the housing for fluids that have been screened;

said means for flexibly and movably supporting being connected between said housing and said screening member; and

conduit means connected betwen said outlet and the inside of said tubular screening member whereby materials may flow into said housing, through said screening member, thence out of said housing through said conduit means.

9. A screening apparatus according to claim 8 wherein said means for flexibly and movably supporting is a universal joint.

10. A screening apparatus according to claim 8 further comprising second means for removably supporting said screening member in tubular shape, and said means for flexibly and movably supporting being connected between said housing and said second means for supporting.

11. A screening apparatus according to claim 8 wherein said conduit means includes a flexible conduit connected between said housing and said tubular screening member.

(References on following page) References Cited UNITED STATES PATENTS FOREIGN PATENTS 465,783 6/1950 Canada. Hebem REUBEN FRIEDMAN, Primary Examiner. Wachenberg 210391 X 5 I AD E E Little 210 398 E Asslstant xammer.

Golucke et a1. 210-384 X Cressey et a1. 118603 US. Cl. X.R. 21U385, 391 

